Flame-retardant resin composition

ABSTRACT

A flame-retardant (C) of a nuclearly alkylated aromatic phosphoric acid ester of the following formula (I) and a fluororesin (D) such as polytetrafluoroethylene are added to 100 parts by weight of a mixture of thermoplastic resins comprising an aromatic polycarbonate (A) and a styrenic resin (B) comprising at least a rubber-modified styrenic resin: ##STR1## wherein (i) at least one of R 1  to R 4  is either a 2,3-, a 3,4-, or 3,5-dialkylphenyl group, each alkyl group having 1 to 3 carbon atoms, A is a phenylene group, n denotes an integer of 0 to 5, and R 1  to R 4  contain both the dialkylphenyl group and a monoalkylphenyl group; or (ii) at least one of R 1  to R 4  is a phenyl group substituted with 1 to 5 alkyl groups each having 1 to 4 carbon atoms, A is 1,3-phenylene group and n denotes an integer of 1 to 5. The flame-retardant (C) may be a mixture of the compound (i) and the compound (ii).

FIELD OF THE INVENTION

The present invention relates to a polycarbonate-containingflame-retardant resin composition which has excellent moldingprocessability (moldability) properties such as melt fluidity.

BACKGROUND OF THE INVENTION

A mixture of a polycarbonate and a styrenic resin such as ABS resin, SANresin and so forth has high heat resistance and impact resistance, sothat it is generally used, as a polymer alloy, for various shaped ormolded articles such as parts for an automobile, electric products,electronic products, and the like. When the polymer alloy is employedfor a housing, an enclosure, a chassis or the like of electric orelectronic parts or office automation (OA) apparatus or instruments,flame-retardancy or fire-resistance is required of such a polymer alloy.

In particular, for increasing the safety of a product, a standardqualification of V-0 or 5 V is recently frequently required of a shapedarticle of an OA apparatus or a home electric product. While the V-0 or5 V standard is the highest flame-retardancy level according to theSubject 94 of Underwriter's Laboratory Co., Ltd. (hereinafter brieflyreferred to as UL), it is used as the flame-retardancy standard inU.S.A.

On the other hand, in order to decrease the amount of material used,miniaturization and also making the part or the housing thinner isuseful. Such part or housing has, however, a risk of a fire drip arisingfrom the thinned part of the shaped article accompanied with burning(combustion), and thus spreading fire to another inflammable orcombustible substance. Accordingly, a flame-retardant resin compositionis also required for such a higher flame resistance or flame-retardancyso as not to cause a flame drip.

For imparting the flame-retardancy, a halogen-containing flame-retardantis usually added to a polymer alloy comprising a polycarbonate and astyrenic resin. As the halogen-containing flame-retardant, there mayfrequently be employed a combination of a bromine-containingflame-retardant exemplified as tetrabromobisphenol A or its oligomer, abrominated epoxy oligomer, and a flame-retarding-auxiliary comprising,as a main component, a metallic oxide exemplified as antimony trioxide.It is, however, pointed out by an organization for environmentalprotection in Europe that, among such bromine-containingflame-retardants, use of decabromodiphenyl ether (DBDPE) oroctabromodiphenyl ether (OBDPE) possibly generates toxic dibenzodioxinwith burning of the resin composition. Therefore, anon-halogen-containing flame-retardant is useful for makingflame-retardant (flame-proofing) resin.

As the non-halogen-containing flame-retardant, a phosphorus-containingflame-retardant, specifically a flame-retardant comprising an aromaticphosphoric acid ester is employed. For example, U.S. Pat. No. 5,061,745corresponding to Japanese Patent Application Laid-open No. 32154/1990(JP-A-2-32154) discloses the use of a flame-retardant comprising amonomeric phosphoric acid ester in combination withpolytetrafluoroethylene as a flame-retarding-auxiliary. U.S. Pat. No.5,204,394 discloses an addition of an oligomeric phosphoric acid esterto a mixture of a polycarbonate and a styrenic resin. Further, U.S. Pat.No. 5,122,556 discloses the use of a polycarbonate and a flame-retardantof a dimeric phosphoric acid ester. Moreover, an addition of suchflame-retardant comprising a phosphoric acid ester to a polymer alloycomprising a polycarbonate and a styrenic resin is also disclosed inJapanese Patent Application Laid-open Nos. 62556/1986 (JP-A-61-62556),4746/1987 (JP-A-62-4746), 115262/1990 (JP-A-2-115262), 298554/1992(JP-A-4-298554), 179123/1993 (JP-A-5-179123), 262940/1993(JP-A-5-262940), 279531/1993 (JP-A-5-279531) and so on.

Use of these flame-retardants comprising an aromatic substituted ornon-substituted phosphoric acid ester can impart flame-retardancy andimpact resistance suitably to a polymer alloy comprising a polycarbonateand a styrenic resin. Therefore, some of such resin composition as amolding material for a home electric apparatus or an OA apparatus hasbeen commercially implemented.

The polymer alloy comprising the non-halogen-containing flame-retardanthas, however, frequently poor melt fluidity during the molding process.Accordingly, a shaped article or molded article requiring not onlyminiaturization but also lightening and thinning can hardly be producedwith high efficiency, by imparting high fluidity (flowability) to thepolymer alloy.

Further, the polymer alloy is liable to become attached to a mold of themolding machine and thus a frequent cleaning of the mold is required.Deterioration or degradation by residence of the resin by, for example,heat or thermal degradation of the flame-retardant is apt to occurduring the molding process.

Furthermore, even if using a polymer alloy having comparatively highmelt fluidity, the resultant molded article may have poor lightresistance (light stability) and is liable to be discolored. The heatresistance, impact resistance, mechanical strength and the like of themolded article is likely to be decreased when increasing or enhancingthe melt fluidity. For instance, the heat resistance andflame-retardancy of the shaped article is liable to be decreased with anincreased ratio of the styrenic resin relative to the polycarbonate,although the melt fluidity is enhanced. Accordingly, the lightresistance, heat resistance and impact resistance and the mechanicalstrength of the molded article can hardly be increased with maintaininghigh melt fluidity.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide aflame-retardant resin composition, whereby high flame-retardancy can beimparted to a molded article, and which has high melt fluidity.

It is another object of the invention to provide a flame-retardant resincomposition whereby even a molded article having a thin portion can bemolded with high accuracy.

A still another object of the present invention is to provide, in apolymer alloy system comprising a polycarbonate and a styrenic resin, aresin composition wherein flame drip during burning can be inhibited orsuppressed and which has high flame-retardancy or flame resistance.

A further object of the invention is to provide a flame-retardant resincomposition which is useful for obtaining a shaped article excellent inflame-retardancy, heat resistance, impact resistance and mechanicalstrength.

It is yet another object of the present invention to provide aflame-retardant resin composition which has high melt fluidity and isuseful for obtaining a molded article having not only highflame-retardancy but also excellent light resistance.

Yet another object of the present invention is to provide aflame-retardant resin composition which is useful for obtaining a shapedarticle excellent in flame-retardancy, light resistance, heatresistance, impact resistance and mechanical strength.

The present inventor made intensive investigations to achieve the aboveobjects and, as a result, found that when an aromatic phosphoric acidester having an alkyl group substituted on a specific position of thephenyl group is used as a non-halogen-containing flame-retardant, notonly the flame-retardancy but also the melt fluidity can be improved,and thus a shaped article (molded article) can be molded in highaccuracy. Further, he found that by using a specific nucleus-substitutedaromatic phosphoric acid ester having 1,3-phenylene group as thenon-halogen-containing flame-retardant, a resin composition having highmelt fluidity can be obtained, and a shaped article having highflame-retardancy, and further high light resistance, can be obtained inhigh accuracy. The present invention has been accomplished based onthese findings.

Accordingly, a flame-retardant resin composition of the presentinvention comprises (A) an aromatic polycarbonate, (B) a styrenic resin,(C) a flame-retardant of an aromatic phosphoric acid ester shown by thefollowing formula (I) ##STR2## wherein R¹, R², R³ and R⁴ independentlyrepresent a phenyl group which may be substituted with an alkyl grouphaving 1 to 4 carbon atoms, A represents an aromatic residue, and ndenotes an integer of 0 to 5, and (D) a fluororesin, wherein saidflame-retardant (C) is (i) a compound shown by the formula (I) where R¹to R⁴ independently represent a phenyl group substituted with 0 to 3alkyl groups each having 1 to 4 carbon atoms and at least one of R¹ toR⁴ is a 2,4-dialkylphenyl group, a 3,4-dialkylphenyl group or a3,5-dialkylphenyl group, (ii) a compound shown by the formula (I) whereA is 1,3-phenylene group, n denotes an integer of 1 to 5 and at leastone of R¹ to R⁴ is a phenyl group substituted with 1 to 5 alkyl groupseach having 1 to 4 carbon atoms, or (iii) a mixture of the compound (i)and the compound (ii).

In the compound (i) of the formula (I), the alkyl group may be an alkylgroup having 1 to 3 carbon atoms such as methyl group and ethyl group,and A may be a phenylene group. The proportion of the amount of the2,4-dialkylphenyl group, the 3,4-dialkylphenyl group and the3,5-dialkylphenyl group is, for example, about 50 mole percent or morebased on the total amount of R¹, R², R³ and R⁴, and in the phenyl groupsrepresented by R¹, R², R³ and R⁴, the ratio of the amount of the2,4-dialkylphenyl group, the 3,4-dialkylphenyl group and the3,5-dialkylphenyl group relative to the amount of monoalkylphenyl groupsmay frequently be such that the former/the latter is about 50/50 to90/10 (mole percent).

In the compound (ii) of the formula (I), the alkyl group may be a methylgroup or an ethyl group. In such case, at least one of R¹, R², R³ and R⁴may be a phenyl group substituted with 2 alkyl groups each having 1 to 3carbon atoms, and n may be an integer of 1 to 3.

The styrenic resin (B) includes, for example, a non-rubber-modifiedstyrenic resin such as SAN resin (AS resin), and a rubber-modifiedstyrenic resin such as ABS resin. The fluororesin (D) such as apolytetrafluoroethylene may usually be employed in a powdery or granularform.

DETAILED DESCRIPTION OF THE INVENTION [Aromatic Polycarbonate (A)]

The aromatic polycarbonate (A) includes various polymers, for example apolycarbonate obtainable by a reaction of a dihydric phenol compound andphosgene (phosgene method), or by a reaction of a dihydric phenolcompound and a carbonic diester (transesterification method). Asexamples of the dihydric phenol compound, there may be mentioned anoptionally substituted bis (hydroxyaryl) alkane such as bis(4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis(4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 1,1-bis(4-hydroxyphenyl) isobutane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis(4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-t-butylphenyl)propane, 2,2-bis (3,5-dimethyl- 4-hydroxyphenyl) propane, 2,2-bis(4-hydroxy-3-cyclohexylphenyl)propane and 2,2-bis(4-hydroxy-3-methoxyphenyl) propane; an optionally substituted bis(hydroxyaryl) cycloalkane such as 1,1-bis (4-hydroxyphenyl)cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis(4-hydroxyphenyl) cyclododecane and others; a dihydroxyaryl ether suchas 4,4'-dihydroxyphenyl ether and 4,4'-dihydroxy-3,3'-dimethylphenylether; a dihydroxydiaryl sulfide such as 4,4'-dihydroxydiphenyl sulfideand 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; a dihydroxydiarylsulfoxide such as 4,4'-dihydroxydiphenyl sulfoxide and4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; a dihydroxydiarylsulfone such as 4,4'-dihydroxydiphenyl sulfone and4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone; a dihydroxydiaryl ketonesuch as bis (4-hydroxyphenyl) ketone and bis (4-hydroxy-3-methylphenyl)ketone; 1,4-bis (4-hydroxyphenylsulfonyl) benzene, 4,4'-bis(4hydroxyphenylsulfonyl) benzene, 1,2-bis (4-hydroxyphenoxy) ethane,phenolphthalein and others. These dihydric phenol compounds can be usedsingly or in combination.

Preferred examples of the dihydric phenol compound include a bisphenolwhereby an aromatic polycarbonate having high heat resistance can beobtained. As such bisphenol, there may be mentioned, for instance, a bis(hydroxyphenyl)alkane such as 2,2-bis (4-hydroxyphenyl) propane, a bis(hydroxyphenyl) cycloalkane such as bis (4-hydroxyphenyl) cyclohexane, adihydroxydiphenyl sulfide, a dihydroxydiphenyl sulfone, adihydroxydiphenyl ketone and so on. Typically preferred dihydric phenolcompound includes, for example, 2,2-bis (4hydroxyphenyl) propane(namely, bisphenol A) with which a bisphenol A type aromaticpolycarbonate can be formed.

In the preparation of the bisphenol A type aromatic polycarbonate, apart of bisphenol A can be replaced by another dihydric phenol compoundinsofar as the heat resistance, mechanical strength and the like are notadversely affected.

The molecular weight of the polycarbonate is, for example, as aviscosity-average molecular weight measured at 20° C. by using methylenechloride, about 15,000 to 50,000, preferably about 18,000 to 40,000 andmore preferably about 20,000 to 30,000. When the molecular weight isless than 15,000, the impact resistance of the shaped article is liableto be decreased, and when it exceeds 50,000, the fluidity (flowability)is apt to be decreased.

The limiting-viscosity of the polycarbonate is, for instance, about 0.3to 0.7 dl/g, and preferably about 0.3 to 0.65 dl/g in methylene chlorideat 20° C.

[Styrenic resin (B)]

The styrenic resin (B) includes a non-rubber-modified styrenic resin(B1) which does not include a rubber component and a rubber-modifiedstyrenic resin (B2). The rubber-modified styrenic resin (B2) may be amixed composition (B2a) of a rubber component and a styrenic resin, or agrafted polymer (B2b) obtainable by graft-polymerizing a styrenicmonomer or a mixture of vinyl monomer comprising a styrenic monomer andnon-styrenic vinyl monomer to a rubber component (B21).

The non-rubber-modified styrenic resin (B1) include a homo- orco-polymer of an aromatic vinyl monomer (B1a) and a copolymer obtainableby polymerizing an aromatic vinyl monomer (B1a) and a copolymerizablenon-styrenic vinyl monomer.

As examples of the aromatic vinyl monomer (B1a), there may be mentioneda styrenic monomer such as styrene, an alkyl-substituted styrene (forinstance, o-methylstyrene, p-methylstyrene, m-methylstyrene,2,4-dimethylstyrene, p-ethylstyrene, p-t-butylstyrene and the like), anα-alkyl-substituted styrene (e.g. α-methylstyrene,α-methyl-p-methylstyrene, etc.) a halogenated styrene (for instance,o-chlorostyrene, p-chlorostyrene, etc.) and others. Preferred examplesof the aromatic vinyl monomer include styrene, p-methylstyrene andα-methylstyrene, particularly, styrene and α-methylstyrene. Thesearomatic vinyl monomers can be employed singly or in combination.

The non-styrenic vinyl monomer includes a copolymerizable vinyl monomersuch as vinyl cyanide monomer (B1b) (for example, acrylonitrile,methacrylonitrile), other copolymerizable vinyl monomer (B1c) [e.g. a(meth) acrylic monomer (for instance, a (meth) acrylic acid ester or(meth) acrylic ester of an alkyl having about 1 to 10 carbon atoms suchas methyl methacrylate, ethyl acrylate and butyl acrylate, a (meth)acrylic ester having a functional group such as 2-hydroxyethylmethacrylate and 2-hydroxypropyl methacrylate, (meth) acrylic acid andthe like), maleic anhydride, N-substituted maleimide and so on].

Preferred examples of the non-styrenic monomer include (meth)acrylonitrile, (meth) acrylic monomer (e.g., (meth) acrylic acid esterof an alkyl having about 1 to 4 carbon atoms such as methylmethacrylate), maleic anhydride, N-substituted maleimide and others,specifically acrylonitrile, an alkyl (meth) acrylate such as methylmethacrylate and so on. Such non-styrenic monomers can also be employedsingly or in combination.

The styrenic resin (B1) may, for example, be a homo- or co-polymer of anaromatic vinyl monomer (e.g. polystyrene), or may frequently be (1) acopolymer obtainable by polymerizing the styrenic monomer (B1a) and thevinyl cyanide monomer (B1b) such as acrylonitrile [for example, anacrylonitrile-styrene copolymer (hereinafter briefly referred to as SANresin) and others], (2) a copolymer obtainable by polymerizing thestyrenic monomer (B1a) and the alkyl (meth) acrylate (B1c) (forinstance, a styrene-methyl methacrylate copolymer and so on), (3) acopolymer obtainable by polymerizing the styrenic monomer (B1a), thevinyl cyanide monomer (B1b) and the copolymerizable vinyl monomer (B1c)such as an alkyl (meth) acrylate (e.g. a styrene-acrylonitrile-methylmethacrylate copolymer, etc.), (4) a styrene-maleic anhydride copolymer,a styrene-N-substituted maleimide copolymer and others.

As the preferred styrenic resin (B1), there may be mentioned, forinstance, SAN resin, a styrene-acrylonitrile-(meth) acrylic acid alkylester copolymer and so on. The non-rubber-modified styrenic resin (B1)can be used singly or in combination.

The proportion of each monomer for preparing the copolymer may beselected from a range, as long as the melt fluidity, the heat resistanceand impact resistance of the molded article are not impaired, and is,for example, about 50 to 90% by weight (preferably about 55 to 85% byweight and more preferably about 60 to 80% by weight) of the aromaticvinyl monomer (B1a), about 10 to 40% by weight (preferably about 15 to35% by weight and more preferably about 20 to 30% by weight) of thevinyl cyanide monomer (B1b), and about 0 to 40% by weight (preferablyabout 0 to 30% by weight and more preferably about 0 to 20% by weight)of the copolymerizable vinyl monomer (B1c) such as a (meth) acrylicmonomer. Use of the aromatic vinyl monomer (B1a) in an amount of lessthan 50% by weight may possibly cause coloring or deterioration(degradation) of the molded article, and use in a proportion of morethan 90% by weight is liable to decrease the heat resistance and thechemical resistance of the shaped article.

Further, when the vinyl cyanide (B1b) is used in a proportion of lessthan 10% by weight, the chemical resistance of the shaped article is aptto be decreased or reduced, while when it exceeds 40% by weight, theheat stability of the shaped article is likely to be reduced. Moreover,use of the copolymerizable vinyl monomer (B1c) such as a (meth) acrylicmonomer in an amount of more than 40% by weight may occasionallydecrease the melt fluidity or the properties or characteristics of theshaped article.

As the rubber component in the rubber-modified styrenic resin (B2),there may be mentioned, for example, a non-styrenic rubber-like polymercontaining no styrene unit such as a polybutadiene rubber, abutadiene-isoprene rubber, a butadiene-acrylonitrile copolymer, anethylene-propylene rubber, an EPDM rubber (anethylene-propylene-nonconjugate diene rubber), a polyisoprene rubber, apolychloroprene rubber, an acrylic rubber and an ethylene-vinyl acetatecopolymer; a styrenic rubber-like polymer containing a styrene unit suchas a styrene-butadiene copolymer and a styrene-butadiene blockcopolymer. These rubber-like polymer can be employed singly or incombination.

Preferred examples of the rubber component include a polybutadiene, abutadiene-acrylonitrile copolymer, an ethylene-propylene rubber, an EPDMrubber, an acrylic rubber, a styrene-butadiene copolymer and astyrene-butadiene block copolymer. A polymer containing a butadiene unit(for instance, a polybutadiene, a styrene-butadiene copolymer) mayfrequently be used as the rubber component.

The glass-transition temperature Tg of the rubber component is nothigher than about 0° C., preferably about -150° C. to 0° C., and morepreferably about -100° C. to -10° C. Where the glass-transitiontemperature of the rubber component exceeds 0° C., the impact strengthof the shaped article (molded article) is liable to be decreased orimpaired.

The rubber-modified styrenic resin may comprise a mixture of the rubbercomponent and the styrenic resin, or may preferably be a high impactresistant styrenic resin obtainable by graft-polymerizing at least astyrenic monomer to a rubber component. As examples of therubber-modified styrenic resin, there may be mentioned a high impactresistant polystyrene (HIPS) obtainable by polymerizing styrene to apolybutadiene, ABS resin obtainable by polymerizing acrylonitrile andstyrene to a polybutadiene, AAS resin obtainable by polymerizingacrylonitrile and styrene to a acrylic rubber, ACS resin obtainable bypolymerizing acrylonitrile and styrene to a chlorinated polyethylene,AES resin obtainable by polymerizing acrylonitrile and styrene to anethylene-propylene rubber (or EPDM rubber), a terpolymer obtainable bypolymerizing acrylonitrile and styrene to an ethylene-vinyl acetatecopolymer, MBS resin obtainable by polymerizing methyl methacrylate andstyrene to a polybutadiene and so on. These rubber-modified styrenicresins can be employed singly or as a mixture of two or more species.

In the rubber-modified styrenic resin (B2), the components other thanthe rubber component and the proportions thereof are frequently incommon with those of the non-rubber-modified styrenic resin. The ratioof the amount of the rubber component (B21) relative to the amount ofthe polymerizable monomer containing at least an aromatic vinyl monomercan be selected from a wide range depending on the characteristics ofthe rubber-modified styrenic resin, and is, for example, such that theformer/the latter equals about 5/95 to 65/35 (% by weight), preferablyabout 10/90 to 60/40 (% by weight), more preferably about 15/85 to 50/50(% by weight), and frequently about 10/90 to 65/35 (% by weight).Graft-polymerization in such ratio can afford a high impact resistantgrafted polymer containing the rubber component corresponding to theratio. In the rubber-modified styrenic resin (B2), the composition ofthe polymerizable monomers is, for instance, about 20 to 90% by weightand preferably about 21 to 85% by weight of the aromatic vinyl monomer(B1a), about 10 to 40% by weight and preferably about 14 to 38% byweight of the vinyl cyanide monomer (B1b) and about 0 to 40% by weightand preferably about 0 to 30% by weight of the copolymerizable vinylmonomer (B1c) in many cases.

The mean or average particle size of the rubber component dispersed inthe rubber-modified styrenic resin (B2), particularly in the graftedpolymer, is for instance about 0.05 to 5 μm, preferably about 0.1 to 3μm, and more preferably about 0.1 to 1 μm. When the mean particle sizeof the rubber component is less than 0.05 μm, the impact strength of theshaped article is liable to be decreased, and when it exceeds 5 μm, thegloss or luster and/or surface appearance of the shaped article is aptto be impaired or deteriorated. The rubber component may be dispersed asrubber disperse particles having a plurality of peaks (for example, twopeaks) in the particle size distribution. The styrenic resin (B) maycomprise the non-rubber-modified styrenic resin (B1) alone, but it mayadvantageously comprise at least the rubber-modified styrenic resin(B2), specifically the grafted polymer, for improvement or enhancementof the impact resistance. That is, the preferred examples of thestyrenic resin (B) include (1) the rubber-modified styrenic resin (B2)alone, and (2) a mixed resin composition comprising thenon-rubber-modified styrenic resin (B1) and the rubber-modified styrenicresin (B2). For improving or increasing the melt fluidity and moldingprocessability, a mixture of the non-rubber-modified styrenic resin (B1)and the rubber-modified styrenic resin (B2) can frequently be used asthe styrenic resin (B). The ratio of the non-rubber-modified styrenicresin (B1) relative to the rubber-modified styrenic resin (B2) may beselected from a wide range, and is, for instance, such that theformer/the latter is about 0/100 to 75/25 (% by weight), preferablyabout 0/100 to 60/40 (% by weight), more preferably about 0/100 to 50/50(% by weight), and frequently about 10/90 to 40/60 (% by weight). Use ofthe non-rubber-modified styrenic resin (B1) in a proportion of more than75% by weight is apt to decrease the impact resistance of the shapedarticle, and use of the rubber-modified styrenic resin (B2) in an amountof less than 25% by weight is liable to decrease or impair the impactresistance of the shaped article.

When the styrenic resin (B) is a mixed resin composition of thenon-rubber-modified styrenic resin (B1) such as SAN resin, and therubber-modified styrenic resin (B2) such as ABS resin, the content ofthe rubber component in the styrenic resin (B) is, for instance, about 1to 50% by weight, preferably about 5 to 40% by weight, and morepreferably about 10 to 30% by weight. When using the rubber component ina proportion of less than 1% by weight, the impact resistance of theshaped article may be decreased, and when using it in a proportion ofmore than 50% by weight, decrease of the melt fluidity, or gelation(gelling), coloring and/or deterioration during the molding process areliable to occur.

The non-rubber-modified styrenic resin may be prepared by a conventionalmethod such as emulsion polymerization, solution polymerization, bulkpolymerization, suspension polymerization, and the like. Therubber-modified styrenic resin (grafted polymer) may frequently beprepared by bulk polymerization, suspension polymerization, or emulsionpolymerization. In the polymerization, if necessary, an inert solventsuch as benzene, ethylbenzene, toluene, xylene and a mineral oil, amolecular weight regulator, an antioxidant, a lubricant, a plasticizerand so on may be added.

[Resin Mixture]

By melting and mixing the polycarbonate (A) and the styrenic resin (B),a shaped article having high heat and impact resistance can be obtained.It may probably be because these resins form a polymer alloy. The ratioof the polycarbonate (A) relative to the styrenic resin (B) can beselected from the range according to the species of each of the resinsinsofar as not impairing the heat resistance, the impact resistance, themelt fluidity and the like, and is for example such that the former/thelatter is about 40/60 to 95/5 (% by weight), preferably about 50/50 to95/5 (% by weight) and more preferably about 55/45 to 85/15 (% byweight). The proportion of the polycarbonate (A) relative to thestyrenic resin (B) is frequently such that the former/the latter isabout 50/50 to 90/10 (% by weight), particularly about 60/40 to 90/10 (%by weight). Use of the polycarbonate (A) in a proportion of less than40% by weight is apt to decrease or reduce the heat resistance or theimpact resistance of the shaped article, although the melt fluidity isin high level in such case. When the proportion of the polycarbonate (A)exceeds 95% by weight, the melt fluidity during the molding process isliable to be decreased. The content of the rubber component in the resinmixture is, for instance, about 1 to 30% by weight and preferably about1 to 25% by weight.

[Flame-Retardant (C)]

The flame-retardant (C) is an aromatic phosphoric acid ester shown bythe formula (I). In the formula (I), the alkyl group which may besubstituted on the phenyl group of R¹ to R⁴ includes, for example, alower alkyl group having about 1 to 4 carbon atoms such as methyl,ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl and t-butyl groups.Among these alkyl groups, an alkyl group having 1 to 3 carbon atoms,particularly methyl group and/or ethyl group is preferred. Each of thephenyl groups may be substituted with about 0 to 3, preferably about 1to 3 (for instance, 1 or 2, particularly 2) alkyl groups.

As the aromatic residue represented by A, there may be mentioned, forinstance, an arylene group including a phenylene group such as1,2-phenylene group, 1,3-phenylene group and 1,4-phenylene group,hydroquinone residue, naphthalene residue, etc., bisphenol A residue andso on. Preferred aromatic residue includes an arylene group,specifically a phenylene group. A feature of the present inventionresides in the use of, as the flame-retardant, the compound (i) shown bythe formula (I) wherein R¹ to R⁴ independently represent a phenyl groupsubstituted with 0 to 3 alkyl groups each having 1 to 4 carbon atoms,and two alkyl group are bonded to a specific position of the phenylgroup represented by R¹, R², R³ and R⁴, the compound (ii) shown by theformula (I) wherein A is 1,3-phenylene group, n is an integer of 1 to 5,and at least one of R¹, R², R³ and R⁴ is a phenyl group substituted with1 to 5 alkyl groups each having 1 to 4 carbon atoms, or a mixture of thecompound (i) and the compound (ii).

Hereinafter the compound (i) is illustrated. The numbers of the alkylgroup(s) for each of the phenyl groups is about 0 to 3, and preferablyabout 1 or 2 in the compound (i). In such compound, at least one of thesubstituents R¹ to R⁴ is a 2,4-dialkylphenyl group, a 3,4-dialkylphenylgroup or 3,5-dialkylphenyl group. Preferred examples of thedialkylphenyl group include 2,4-dimethylphenyl group, 3,4-dimethylphenylgroup, 3,5-dimethylphenyl group, 2,4-diethylphenyl group,3,4-diethylphenyl group, 3,5-diethylphenyl group, 2-methyl-4-ethylphenylgroup, 3-methyl-4-ethylphenyl group, 3-methyl-5-ethylphenyl group,2-ethyl-4-methylphenyl group, 3-ethyl-4-methylphenyl group,3-ethyl-5-methylphenyl group, 2,4-dipropylphenyl group,3,4-dipropylphenyl group, 3,5-dipropylphenyl group,2,4-diisopropylphenyl group, 3,4-diisopropylphenyl group,3,5-diisopropylphenyl group and others.

The substituents R¹, R², R³ and R⁴ may independently be a dialkylphenylgroup selected from a 2,4-dialkylphenyl group, a 3,4-dialkylphenyl groupand a 3,5-dialkylphenyl group. Use of the compound where thesubstituents R¹ to R⁴ are respectively a 2,4-dialkylphenyl group, a3,4-dialkylphenyl group and/or a 3,5-dialkylphenyl group, can remarkablyimprove the melt fluidity. Meanwhile, when using the compound where allof the substituents R¹ to R⁴ are 2,6-dialkylphenyl groups, the meltfluidity would not improve so much.

Only if comprising such 2,4-dialkylphenyl group, 3,4-dialkylphenyl groupand/or 3,5-dialkylphenyl group, the substituents R¹ to R⁴ may furthercomprise a phenyl group, a monoalkylphenyl group (for instance,2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, etc.),a 2,3-dialkylphenyl group, a 2,5-dialkylphenyl group, a2,6-dialkylphenyl group (e.g., 2,6-dimethylphenyl group and so on), atrialkylphenyl group (for instance, 2,4,6-trimethylphenyl group) and thelike. The compound (i) shown by the formula (I) may usually contain a2,6-dialkylphenyl group which is a position-isomer relative to the2,4-dialkylphenyl group, 3,4-dialkylphenyl group and 3,5-dialkylphenylgroup, or a phenyl group or a monoalkylphenyl group.

The proportion of the 2,4-dialkylphenyl group, 3,4-dialkylphenyl groupand 3,5-dialkylphenyl group based on the total amount of R¹, R², R³ andR⁴ may be within the range as long as the melt fluidity, the heatresistance and the like are not adversely affected, and is, forinstance, about not less than 50 mole percent, preferably about 60 to100 mole percent, and more preferably about 65 to 100 mole percent. Whenthe proportion of the dialkylphenyl group is less than 50 mole percent,the melt fluidity during the molding process may occasionally bedecreased.

Further, when R¹, R², R³ and R⁴ comprise both a dialkylphenyl group(e.g. a 2,4-dialkylphenyl group, a 2,6-dialkylphenyl group, a3,4-dialkylphenyl group, a 3,5-dialkylphenyl group, and so on) and amonoalkylphenyl group, the ratio of the 2,4-dialkylphenyl group,3,4-dialkylphenyl group and 3,5-dialkylphenyl group relative to themonoalkylphenyl group is such that, for example, the former/the latterequals about 50/50 to 95/5 (mole percent), preferably about 50/50 to90/10 (mole percent), and more preferably about 60/40 to 90/10 (molepercent). The ratio of the dialkylphenyl group relative to themonoalkylphenyl group is frequently such that the former/the latter isabout 60/40 to 80/20 (mole percent). When the ratio of the dialkylphenylgroup is out of the above-mentioned range, the melt fluidity during themolding process may sometimes be impaired or decreased.

The repeating unit n in the compound (i) of the formula (I) may be aninteger of 0 to 5. The compound (i) of the formula (I) wherein therepeating unit n is an integer of 1 to 3, particularly 1 or 2 canadvantageously be used for constituting a flame-retardant of anoligomeric phosphoric acid ester.

The flame-retardant (C) may frequently comprise a mixture of phosphoricacid esters differing in the repeating unit n. The mean or average valueof such repeating unit n is about 0.5 to 2.0, preferably about 1.0 to1.8 and more preferably about 1.2 to 1.7. In the mixture of phosphoricacid esters differing or varying in the repeating unit n, the proportionof the compound where n=1 is, for instance, about 40 to 90 mole percent,preferably about 50 to 80 mole percent, and more preferably about 55 to75 mole percent. To be more concrete, a mixture of the phosphoric acidester oligomers comprises, in many cases, about 0 to 10 mole percent,preferably about 0 to 7 mole percent and more preferably about 0 to 5mole percent of the compound having the repeating unit n of 0, about 40to 90 mole percent, preferably about 50 to 80 mole percent and morepreferably about 55 to 75 mole percent of the compound having therepeating unit n of 1, about 5 to 40 mole percent, preferably about 7 to35 mole percent and more preferably about 10 to 30 mole percent of thecompound having the repeating unit n of 2, and about 5 to 25 molepercent, preferably about 7 to 20 mole percent and more preferably about7 to 17 mole percent of the compound having the repeating unit n of notless than 3. The proportion of the compound having the repeating unit nof not less than 3 may be about 1 to 25 mole percent.

The compound (ii) where A is 1,3-phenylene group and n denotes aninteger of 1 to 5 is explained hereinbelow.

The phenyl group substituted with 1 to 5 alkyl groups each having 1 to 4carbon atoms includes, for instance, a monoalkylphenyl group such as2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group,2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group,2-propylphenyl group, 3-propylphenyl group, 4-propylphenyl group,2-isopropylphenyl group, 3-isopropylphenyl group, 4-isopropylphenylgroup, 2-butylphenyl group, 3-butylphenyl group, 4-butylphenyl group,2-isobutylphenyl group, 3-isobutylphenyl group, 4-isobutylphenyl group,2-s-butylphenyl group, 3-s-butylphenyl group, 4-s-butylphenyl group,2-t-butylphenyl group, 3-t-butylphenyl group, 4-t-butylphenyl group andso on; a 2,3-dialkylphenyl group such as 2,3-dimethylphenyl group,2,3-diethylphenyl group, 2,3-dipropylphenyl group, 2,3-diisopropylphenylgroup, 2-ethyl-3-methylphenyl group, 3-ethyl-2-methylphenyl group andthe like; a 2,4-dialkylphenyl group such as 2,4-dimethylphenyl group,2,4-diethylphenyl group, 2,4-dipropylphenyl group, 2,4-diisopropylphenylgroup, 2-ethyl-4-methylphenyl group, 4-ethyl-2-methylphenyl group andothers; a 2,5-dialkylphenyl group such as 2,5-dimethylphenyl group,2,5-diethylphenyl group, 2,5-dipropylphenyl group, 2,5-diisopropylphenylgroup, 2-ethyl-5-methylphenyl group, 5-ethyl-2-methylphenyl group and soon; a 2,6-dialkylphenyl group such as 2,6-dimethylphenyl group,2,6-diethylphenyl group, 2,6-dipropylphenyl group, 2,6-diisopropylphenylgroup, 2,6-dibutylphenyl group, 2,6-diisobutylphenyl group,2,6-di-s-butylphenyl group, 2,6-di-t-butylphenyl group,2-ethyl-6-methylphenyl group and others; a 3,4-dialkylphenyl group suchas 3,4-dimethylphenyl group, 3,4-diethylphenyl group, 3,4-dipropylphenylgroup, 3,4-diisopropylphenyl group, 3-ethyl-4-methylphenyl group,4-ethyl-3-methylphenyl group and the like; a 3,5-dialkylphenyl groupsuch as 3,5-dimethylphenyl group, 3,5-diethylphenyl group,3,5-dipropylphenyl group, 3,5-diisopropylphenyl group,3-ethyl-5-methylphenyl group and so on; a trialkylphenyl group such as2,3,4-trimethylphenyl group, 2,3,5-trimethylphenyl group,2,3,6-trimethylphenyl group, 2,4,5-trimethylphenyl group,2,4,6-trimethylphenyl group, 3,4,5-trimethylphenyl group,4-ethyl-2,6-dimethylphenyl group, 2,6-diethyl-4-methylphenyl group,4-methyl-2,6-diisopropylphenyl group and others.

The phenyl group substituted with 2 alkyl groups each having 1 to 3carbon atoms such as methyl, ethyl and propyl groups (for instance, adimethylphenyl group such as 2,6-dimethylphenyl group,3,5-dimethylphenyl group, 2,4-dimethylphenyl group and so on) canspecifically be used among these groups. Use of such phenyl groupsubstituted with 2 alkyl groups each having 1 to 3 carbon atoms,particularly a dimethylphenyl group can greatly improve the heatresistance of the shaped article. As the phenyl group substituted with 2alkyl groups each having 1 to 3 carbon atoms, a phenyl group substitutedwith the alkyl groups on the 2- and 6-positions (e.g.,2,6-dimethylphenyl group, 2,6-diethylphenyl group,2-ethyl-6-methylphenyl group, etc.) may frequently be employed.

The substituents R¹, R², R³ and R⁴ may be independently a phenyl groupsubstituted with 1 to 5 alkyl groups each having 1 to 4 carbon atoms.When the compound where the substituents R¹ to R⁴ are the phenyl groupseach substituted with 1 to 5 alkyl groups each having 1 to 4 carbonatoms, the melt fluidity, and the light resistance of the shaped articlecan remarkably be improved or enhanced.

Use of a compound where all of the substituents R¹ to R⁴ arenon-substituted phenyl groups notably decrease or impair the lightresistance of the shaped article. When using a compound where A is1,4-phenylene group, the melt fluidity is decreased and the tensileelongation of the shaped article is reduced.

In the compound (ii), the repeating unit n in the formula (I) may be aninteger of 1 to 5. The compound (ii) of the formula (I) wherein n is aninteger of 1 to 3, particularly 1 or 2, more specifically 1 canadvantageously be used for constituting a flame-retardant of anoligomeric phosphoric acid ester (phosphoric ester).

These flame-retardants (flame-retarders) can be employed singly or incombination. Preferably, the flame-retardant (C) comprises at least thecompound (i). When a mixture of the compound (i) and the compound (ii)is employed as the flame-retardant (C), the ratio of the compound (i)relative to the compound (ii) can be selected from a wide range, and is,for example, such that the former/the latter is about 1/99 to 99/1 (byweight), preferably about 10/90 to 90/10 (by weight) and more preferablyabout 30/70 to 70/30 (by weight).

The flame-retardant shown by the formula (I) can be prepared by variousmethods. By way of illustration, as described in Japanese PatentApplication Laid-open No. 1079/1993 (JP-A-5-1079), the flame-retardantcan be prepared by allowing a phenol compound corresponding to R¹, R²,R³ and R⁴ (for example, phenol, cresol, xylenol and the like) to reactwith phosphorus oxychloride and a dihydric phenol corresponding to thearomatic residue A (e.g., resorcinol, hydroquinone, bisphenol A,1,4-dihydroxybenzene and so on). The ratio of the dialkylphenyl grouprelative to the monoalkylphenyl group or the like can easily becontrolled or adjusted by selecting the species and the amount of thephenol compound corresponding to R¹, R², R³ and R⁴.

The amount of the compound (C) shown by the formula (I) may be aneffective amount to impart the flame-retardancy (fire resistance) to thepolycarbonate (A) and the styrenic resin (B), and is, for example, about5 to 50 parts by weight, preferably about 10 to 30 parts by weight, andmore preferably about 15 to 25 parts by weight relative to 100 parts byweight of the mixed resin composition of the polycarbonate (A) and thestyrenic resin (B). Use of the flame-retardant (C) in a proportion ofless than 5 parts by weight relative to 100 parts by weight of the mixedresin composition can hardly impart high melt fluidity and the highflame-retardancy suited to the UL Standard to the shaped or moldedarticle, and the use in a proportion of more than 50 parts by weight isapt to decrease or impair the heat resistance of the shaped article,although imparting high melt fluidity and flame-retardancy. When theamount of the flame-retardant shown by the formula (I) is about 10 to 25parts by weight relative to 100 parts by weight of the mixed resincomposition, well-balanced various characteristics such as theflame-retardancy, heat resistance, impact resistance, melt fluidity, andothers can be obtained.

[Fluororesin (D)]

The use of the fluororesin (D) can suppress drip of a kindling substanceand a molten mixture, thus the fluororesin (D) acts as aflame-retarding-auxiliary. The fluororesin includes, for example, amono- or copolymer obtainable by polymerizing a fluorine-containingmonomer such as tetrafluoroethylene, chlorotrifluoroethylene, vinylfluoride, vinylidene fluoride, hexafluoropropylene, perfluoroalkyl vinylether and so on; a copolymer obtainable by polymerizing thefluorine-containing monomer and a copolymerizable monomer such asethylene, propylene and acrylate. Practical examples of the fluororesininclude a homopolymer such as polytetrafluoroethylene,polychlorotrifluoroethylene, polyvinylidene fluoride and others; acopolymer such as a tetrafluoroethylene-hexafluoropropylene copolymer, atetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, atetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ethercopolymer, an ethylene-tetrafluoroethylene copolymer, anethylene-chlorotrifluoroethylene copolymer and the like. Thesefluororesins can be employed singly or in combination.Polytetrafluoroethylene (hereinafter referred to as PTFE) can preferablybe used among these fluororesins. The fluororesin may be prepared by aconventional method such as the emulsion polymerization method describedin U.S. Pat. No. 2,393,967.

The fluororesin may be compounded or incorporated into the resincomposition by melting and mixing with the polycarbonate and thestyrenic resin, or may frequently be used in a powdery form, for exampleas a powder or granule having a mean particle size of about 10 to 5,000μm, preferably about 100 to 1,000 μm, and more preferably about 200 to700 μm.

The fluorine-content of the fluororesin may be selected from a rangedepending on the species of the resin insofar as the flame-retardancy orflame resistance can be imparted to the shaped article, and frequentlyis, for instance, about 65 to 75% by weight and preferably about 70 to74% by weight. The apparent density of the powdery or granularfluororesin is, for example, about 0.4 to 0.6 g/cm³, and preferablyabout 0.43 to 0.47 g/cm³. When the fluororesin ispolytetrafluoroethylene, the specific gravity of the fluororesin isabout 2.13 to 2.22 g/cm³, and the melting point is about 326° C. to 328°C.

The flame-retarding-auxiliary (D) may be used in an amount of, forinstance, about 0.05 to 5 parts by weight, preferably about 0.1 to 2parts by weight and more preferably about 0.2 to 1 part by weightrelative to the 100 parts by weight of the resin mixture. When addingthe fluororesin (D) in a proportion of less than 0.05 part by weight,sufficient inhibiting or suppressing effect on the drip of the kindlingsubstance and/or molten drop (drip-inhibiting effect) and thus highflame-retardancy or fire resistance cannot be imparted to the shapedarticle. Addition of the fluororesin in a proportion of more than 5parts by weight may increase the shrinkage of the shaped article byheat, with decreasing the dimensional accuracy during heating process aswell as with increasing cost.

[Other Additives]

The flame-retardant resin composition may also include various additivesincluding, for example, a degradation-inhibitor such as an antioxidant,an ultraviolet-absorber and a light-resistant stabilizer; a lubricant;an antistatic agent; a mold release agent (mold lubricant); aplasticizer; a reinforcing fiber such as a glass fiber, a carbon fiber,a polyamide fiber, an aromatic polyamide fiber, an aromatic polyesterfiber and the like; a filler such as calcium carbonate and talc; and acoloring agent such as a pigment. The amount of such additive may beselected from a range according to the species of the additive insofaras not impairing, for instance, the heat resistance, the impactresistance and the mechanical strength of the shaped article. By way ofillustration, the additive such as an antioxidant is frequently used inan amount of about 5% by weight or less based on the total amount of thecomposition, and the reinforcing agent such as a glass fiber and/or thefiller is usually employed in a proportion of 50% by weight or lessbased on the total amount of the composition.

[Preparation of the Resin Composition]

The flame-retardant (fire resistant) resin composition may be a premixedcomposition obtainable by pre-mixing the polycarbonate (A), the styrenicresin (B), the flame-retardant (C) and the fluororesin (D) with the useof a mixer such as a V-blender, a supermixer, a superfloater or aHenshell mixer. The resin composition is usually a mixture obtainable bymelting and mixing the premixed composition homogeneously. Such mixturecan be obtained by melting and kneading the premixed mixture, with usinga kneading means, at a temperature of, for example, about 200° to 300°C. and preferably about 220° to 280° C., and pelletizing the resultantmixture. As the kneading means, various melting-mixing apparatus such asa kneader, a uniaxial, or biaxial extrusion machine can be employed. Theresin composition may frequently be prepared by melting and extrudingcomponents for the resin composition using a biaxial extruding machineor the like, and pelletizing the resultant material using a pelletizer.

The flame-retardant resin composition of the present invention has highmelt fluidity, whereby not only a miniature article but also alightweight shaped article and a shaped article having a thin portioncan be molded with improved accuracy, and the shaped article can beimparted with high flame-retardancy.

In particular, use of the flame-retardant resin composition comprisingthe flame-retardant corresponding to the case (ii) can further imparthigh light resistance in addition to such excellent flame-retardancy tothe shaped article.

Accordingly, the flame-retardant resin composition is useful as amolding material for various shaped articles such as a housing and/orenclosure of a home electric apparatus, an OA apparatus and the like,and a thin housing or casing of, for instance, a portable telephone.Such shaped article can be produced by a conventional method, forexample by injection molding the pelletized flame-retardant resincomposition using an injection molding machine at, for instance, acylinder temperature of about 220° to 280° C.

The flame-retardant resin composition of the present invention, whichcomprises a specific flame-retardant of aromatic phosphoric acid ester,has excellent flame-retardancy and fire resistance, as well as high meltfluidity.

Accordingly, by using the composition, not only a large size shapedarticle such as a housing but also an article having a thin portion or athinned shaped article can be molded with high accuracy. Further, use ofthe composition can afford a shaped article having improved or enhancedlight resistance, and therefore discoloration or discoloring of theshaped article can be inhibited or suppressed.

Moreover, according to the present invention, where the specificflame-retardant in combination with the fluororesin is added to themixed resin composition of the polycarbonate and the styrenic resin, thedrip from the shaped article during burning can be suppressed and thushigh flame-retardancy can be imparted to the shaped article. Further, ashaped article having excellent heat resistance and impact resistanceand mechanical strength can be obtained. Furthermore, a shaped articlehaving improved or enhanced light resistance in addition to the aboveexcellent characteristics can be obtained.

EXAMPLES

The following examples are merely intended to illustrate the presentinvention in further detail and should not be construed as defining thescope of the invention.

In the following examples, the tensile strength (kg/cm²) and the tensileelongation were measured according to ASTM D-638 at a crosshead speed of5 mm/min., and the bending elasticity (kg/cm²) was measured according toASTM D-790 at a rate of 3 mm per minute. The Izod impact strength(kg•cm/cm) was determined in accordance with ASTM D-256 using a testpiece having a thickness of 1/4 inch and formed with cut notches.

The thermal-deforming temperature (° C.) was measured according to ASTMD-256 by permitting a load of 18.56 kg/cm² to act on a bar having athickness of 1/4 inch. The melt fluidity (g/10 min.) was determinedaccording to Japanese Industrial Standards (JIS) K-7210 under theconditions of a temperature of 230° C. and with a load of 5 kg, and theflame resistance was evaluated in accordance with UL-94 using a testpiece having a thickness of 1/16 inch.

The spiral flow length (bar flow length) (mm) was estimated at acylinder temperature of 240° C., an injection pressure of 750 kgf/cm²,of a width of 20 mm and a thickness of 2 mm.

The light resistance was evaluated by the discoloring degree (ΔE) afterlight-irradiation on a three steps-formed (three-high) color plate (50mm×30 mm×1 mm/2 mm/3 mm-thickness) for 300 hours using a xenon lamp.Further, the water-discoloring resistance was estimated by whether ornot a white spot on the surface of the three steps-formed color platewas formed after being dipped in water at room temperature for one day.

EXAMPLE 1

A mixture of thermoplastic resins was prepared using 70 parts by weightof a polycarbonate resin (manufactured by Idemitsu Petroleum ChemicalsCo., Ltd., IDEMITSU POLYCARBONATE FN2700, viscosity-average molecularweight of 27,000), 10 parts by weight of the followingnon-rubber-modified styrenic resin and 20 parts by weight of thefollowing rubber-modified styrenic resin.

The non-rubber-modified styrenic resin: a copolymer having aweight-average molecular weight of 123,000 obtained byemulsion-polymerizing 75 parts by weight of styrene and 25 parts byweight of acrylonitrile in an aqueous solution of a calciumphosphate-containing dispersing agent according to the method describedin Japanese Patent Publication No. 51962/1987 (JP-B-62-51962).

The rubber-modified styrenic resin: a grafted polymer obtained, inaccordance with the method described in Japanese Patent ApplicationLaid-open No. 320274/1993 (JP-A-5-320274), by emulsion-polymerizing 45parts by weight of styrene and 15 parts by weight of acrylonitrile inthe presence of a rubber component of a polybutadiene rubber and astyrene-butadiene rubber latex.

To 100 parts by weight of the thermoplastic resin mixture, were added 19parts by weight of a flame-retardant of a phosphoric acid ester(manufactured by Daihachi Chemical Industries Co., Ltd., CR733RS), 0.4part by weight of polytetrafluoroethylene (manufactured by DaikinIndustries Co., Ltd., POLYFLON TFE (grade name F-104), mean particlesize of about 500 μm, apparent density of 0.45 g/ml, melting point of326° to 328° C., specific gravity of 2.14 to 2.20, fluorine-content ofabout 76%), 0.2 part by weight of an antioxidant and 0.2 part by weightof a heat stabilizer. The resultant mixture was premixed for 40 minutesusing a V-blender, and the premixed mixture was molten and extruded withthe use of a biaxially kneading-extruding machine and pelletized to givea pellet.

The flame-retardant is the compound of the formula (I), where, in thetotal amount of R¹, R², R³ and R⁴, 70% by weight is 2,4-dimethylphenylgroup, 3,4-dimethylphenyl group and 3,5-dimethylphenyl group, and 30% byweight is methylphenyl group and ethylphenyl group; and A is1,3-phenylene group. The flame-retardant comprises less than 3% byweight of the compound having the repeating unit n of 0 and not lessthan 97% by weight of the compound having the repeating unit n of notless than 1, and which comprises about 70% by weight of the compoundhaving the repeating unit n of 1, about 20% by weight of the compoundhaving the repeating unit n of 2, and about 7% by weight of the compoundhaving the repeating unit n of not less than 3.

The above-obtained pellet was dried in an oven at 80° C. for 4 hours ormore, and the dried pellet was injection-molded using an injectionmolding machine having a mold clamping force of 100 ton at a temperatureof 240° C. and at a screw rotating rate of 80 rpm to give a test piece(ASTM No. 2 dumbbell piece, a bar (1/4 inch in thickness, 126 mm inlength), and a test piece for UL burning test (126 mm×126 mm×1.6 mm inthickness)).

EXAMPLE 2

Test pieces were obtained in the same manner as Example 1, except thatthe thermoplastic resin composition was prepared by using (a) 80 partsby weight of a polycarbonate resin (manufactured by Idemitsu PetroleumChemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700, viscosity-averagemolecular weight of 27,000), (b) 10 parts by weight of a copolymer(weight-average molecular weight of 90,000), as a non-rubber-modifiedstyrenic resin, obtained by suspension-polymerizing 15 parts by weightof styrene, 50 parts by weight of α-methylstyrene and 25 parts by weightof acrylonitrile, and (c) 10 parts by weight of a grafted copolymer, asa rubber-modified styrenic resin, obtained by emulsion-polymerizing 56parts by weight of styrene and 19 parts by weight of acrylonitrile inthe presence of a rubber component (25 parts by weight as a solid basis)of a polybutadiene rubber and a styrene-butadiene copolymer rubberlatex.

Comparative Example 1

By repeating the procedure of Example 1, test pieces were obtainedexcept for using 16 parts by weight of a flame-retardant of anon-substituted aromatic phosphoric acid ester (manufactured by DaihachiChemical Industries Co., Ltd., CR733S) where in the formula (I), R¹, R²,R³ and R⁴ are non-substituted phenyl groups, and n is 0 to 4, instead of19 parts by weight of the flame-retardant of Example 1. In theflame-retardant of the non-substituted aromatic phosphoric acid ester, Ais 1,3-phenylene group, and the flame-retardant comprises about 3% ofthe compound having the repeating unit n of 0, about 70% of the compoundhaving the repeating unit n of 1, about 20% of the compound having therepeating unit n of 2, and about 7% of the compound having the repeatingunit n of not less than 3. For adjusting the content of phosphorous inthe composition to the same with that in the composition of Example 1,the flame-retardant of non-substituted aromatic phosphoric acid esterwas added in an amount of 16 parts by weight.

Comparative Example 2

Test pieces were obtained in the same manner as Example 1, except foremploying a flame-retardant of the non-substituted aromatic phosphoricacid ester used in Comparative Example 1 in a proportion of 19 parts byweight, while such amount of the retarder was the same as Example 1.

Comparative Example 3

By using 19 parts by weight of a flame-retardant of a dimericsubstituted aromatic phosphoric acid ester (manufactured by DaihachiChemical Industries Co., Ltd., PX201) in lieu of 19 parts by weight ofthe flame-retardant of aromatic phosphoric acid ester of Example 1, testpieces were prepared in the same manner as Example 1. Theflame-retardant is an aromatic phosphoric acid ester of the formula (I),where R¹, R², R³ and R⁴ are 2,6-dimethylphenyl groups, A is1,4-phenylene group and n=1.

EXAMPLE 3

Test pieces were prepared in the similar manner as in Example 1 exceptthat 10 parts by weight of the following non-rubber-modified styrenicresin and 10 parts by weight of the following rubber-modified styrenicresin were used relative to 80 parts by weight of a polycarbonate resin(manufactured by Idemitsu Petroleum Chemicals Co., Ltd., IDEMITSUPOLYCARBONATE FN2700, viscosity-average molecular weight of 27,000), andthat the flame-retardant used in Example 1 was employed in an amount of23 parts by weight, and the fluororesin used in Example 1 was employedin a proportion of 0.6 part by weight.

The non-rubber-modified styrenic resin: a copolymer having aweight-average molecular weight of 140,000 obtained by bulk-polymerizing63 parts by weight of α-methylstyrene, 10 parts by weight of styrene, 23parts by weight of acrylonitrile and 4 parts by weight of methylmethacrylate.

The rubber-modified styrenic resin: a grafted copolymer obtained byemulsion-polymerizing 45 parts by weight of styrene and 15 parts byweight of acrylonitrile in the presence of a polybutadiene rubber latex(40 parts by weight as a solid basis).

EXAMPLE 4

By employing 10 parts by weight of the non-rubber-modified styrenicresin of Example 2 instead of the non-rubber-modified styrenic resin ofExample 1, and 20 parts by weight of the rubber-modified styrenic resinof Example 2 in lieu of the rubber-modified styrenic resin of Example 1,and further by using the fluororesin in a proportion of 0.2 part byweight, test pieces were prepared in the same manner as Example 1.

EXAMPLE 5

Test pieces were obtained in the similar manner as Example 1, except forusing 20 parts by weight of the non-rubber-modified styrenic resin ofExample 2 and 20 parts by weight of the rubber-modified styrenic resinof the Example 2 relative to 60 parts by weight of a polycarbonate resin(manufactured by Idemitsu Petroleum Chemicals Co., Ltd., IDEMITSUPOLYCARBONATE FN2700, viscosity-average molecular weight of 27,000), andfor employing the flame-retardant in an amount of 17 parts by weight.

EXAMPLE 6

The procedure of Example 1 was followed to obtain test pieces exceptthat 80 parts by weight of a polycarbonate resin (manufactured byIdemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 10 parts by weight of thenon-rubber-modified styrenic resin of Example 1, and 10 parts by weightof the rubber-modified styrenic resin of Example 1 were used, and thatthe amount of the flame-retardant of Example 1 was 40 parts by weightand the proportion of the fluororesin of the Example 1 was 0.2 part byweight.

Comparative Example 4

By using 40 parts by weight of the polycarbonate resin of Example 1, 30parts by weight of the non-rubber-modified styrenic resin of Example 3and 30 parts by weight of the rubber-modified styrenic resin of Example3, and employing the flame-retardant of Comparative Example 2 in anamount of 19 parts by weight, test pieces were obtained in the samemanner as Example 1.

Comparative Example 5

Test pieces were obtained in the similar manner as Example 1 except foremploying 95 parts by weight of the polycarbonate resin of Example 1,2.5 parts by weight of the non-rubber-modified styrenic resin of Example2 and 2.5 parts by weight of the rubber-modified styrenic resin ofExample 2, and for using 19 parts by weight of the flame-retardant ofComparative Example 3.

EXAMPLE 7

The procedure of Example 1 was repeated to obtain test pieces, exceptfor employing 15 parts by weight of the non-rubber-modified styrenicresin of Example 1 (SAN resin) and 15 parts by weight of therubber-modified styrenic resin of Example 1 (ABS resin) instead of 30parts by weight of the styrenic resin (B) of Example 1.

EXAMPLE 8

By using 20 parts by weight of the non-rubber modified styrenic resin ofExample 1 (SAN resin) and 10 parts by weight of the rubber-modifiedstyrenic resin of Example 1 (ABS resin) in lieu of 30 parts by weight ofthe styrenic resin (B) of Example 1, test pieces were obtained in thesame manner as Example 1.

The characteristics of the test pieces each obtained in Examples 1 to 8and Comparative Examples 1 to 5 were evaluated. The results are setforth in Table 1.

In the line of "Species of styrenic resin" in Table 1, the styrenicresin used in Example 1, the styrenic resin employed in Example 2 andthe styrenic resin used in Example 3 are designated by the symbols"(1)", "(2)" and "(3)" respectively, and the total amount of thenon-rubber-modified styrenic resin and the rubber-modified styrenicresin is shown in the line of "Amount of styrenic resin". In the line of"Species of flame-retardant", the flame-retardants respectively used inExample 1, Comparative Example 1 and Comparative Example 3 areseparately indicated by the symbols "(1)", "(2)" and "(3)".

                                      TABLE 1                                     __________________________________________________________________________                    Comp.                                                                             Comp.                                                                             Comp.           Comp.                                                                             Comp.                                       Ex. 1                                                                            Ex. 2                                                                            Ex. 1                                                                             Ex. 2                                                                             Ex. 3                                                                             Ex. 3                                                                            Ex. 4                                                                            Ex. 5                                                                            Ex. 6                                                                            Ex. 4                                                                             Ex. 5                                                                             Ex. 7                                                                            Ex. 8                      __________________________________________________________________________    Polycarbonate                                                                           70 80 70  70  70  80 70 60 80 40  95  70 70                         Species of                                                                              (1)                                                                              (2)                                                                              (1) (1) (1) (3)                                                                              (2)                                                                              (2)                                                                              (1)                                                                              (3) (2) (1)                                                                              (1)                        styrenic resin                                                                Amount of 30 20 30  30  30  20 30 40 20 60  5   30 30                         styrenic resin                                                                Species of flame-                                                                       (1)                                                                              (1)                                                                              (2) (2) (3) (1)                                                                              (1)                                                                              (1)                                                                              (1)                                                                              (2) (3) (1)                                                                              (1)                        retarder                                                                      Amount of flame-                                                                        19 19 16  19  19  23 19 17 40 19  19  19 19                         retarder                                                                      Fluororesin                                                                             0.4                                                                              0.4                                                                              0.4 0.4 0.4 0.6                                                                              0.2                                                                              0.4                                                                              0.2                                                                              0.4 0.4 0.4                                                                              0.4                        Tensile strength                                                                        680                                                                              730                                                                              630 610 690 710                                                                              690                                                                              620                                                                              540                                                                              480 790 690                                                                              700                        Tensile elongation                                                                      38 20 50  121 36  28 25 62 110                                                                              110 15  28 21                         Bending elasticity                                                                      289                                                                              296                                                                              278 252 292 280                                                                              283                                                                              265                                                                              210                                                                              213 323 298                                                                              301                        (x 10.sup.2)                                                                  Impact resistance                                                                       6.0                                                                              6.3                                                                              9.2 7.5 10.5                                                                              7.2                                                                              5.9                                                                              8.1                                                                              -- 5.0 13.0                                                                              5.5                                                                              5.0                        Thermal deforming                                                                       77 85 80  76  85  76 81 72 70 68  95  78 79                         temperature (°C.)                                                      Melt fluidity                                                                           26 20 14  18  10  28 15 25 30 50  5   28 30                         (MI)                                                                          Bar flow length                                                                         300                                                                              253                                                                              240 230 210 315                                                                              247                                                                              282                                                                              331                                                                              510 110 310                                                                              320                        (mm)                                                                          Flame resistance                                                                        v-0                                                                              v-0                                                                              v-0 v-0 v-0 v-0                                                                              v-0                                                                              v-1                                                                              v-0                                                                              v-2 v-0 v-0                                                                              v-0                        (UL)                                                                          __________________________________________________________________________

As apparent from Table 1, the compositions obtained in Examples 1 to 8are excellent in flame-retardancy, particularly in the melt fluidity, incomparison with those obtained in Comparative Examples 1 to 4, and thusare useful for molding a large sized or thin shaped article. Meanwhile,the composition obtained in Comparative Example 4 has poorflame-retardancy although having high melt fluidity, and the compositionobtained in Comparative Example 5 has low melt fluidity although havinghigh heat resistance.

EXAMPLE 9

A mixture of thermoplastic resins was prepared using 70 parts by weightof a polycarbonate resin (manufactured by Idemitsu Petroleum ChemicalsCo., Ltd., IDEMITSU POLYCARBONATE FN2700, viscosity-average molecularweight of 27,000), 10 parts by weight of the followingnon-rubber-modified styrenic resin and 20 parts by weight of thefollowing rubber-modified styrenic resin.

The non-rubber-modified styrenic resin: a copolymer having aweight-average molecular weight of 123,000 obtained bysuspension-polymerizing 75 parts by weight of styrene and 25 parts byweight of acrylonitrile in an aqueous solution of a calciumphosphate-containing dispersing agent according to the method describedin Japanese Patent Publication No. 51962/1987 (JP-B-62-51962).

The rubber-modified styrenic resin: a grafted polymer obtained,according to the method described in Japanese Patent ApplicationLaid-open No. 320274/1993 (JP-A-5-320274), by emulsion-polymerizing 45parts by weight of styrene and 15 parts by weight of acrylonitrile inthe presence of a polybutadiene rubber latex (40 parts by weight as asolid basis).

To 100 parts by weight of the thermoplastic resin mixture, were added 19parts by weight of a flame-retardant of a phosphoric acid ester(manufactured by Daihachi Chemical Industries Co., Ltd., PX200), 0.4part by weight of polytetrafluoroethylene (manufactured by DaikinIndustries, Co., Ltd., POLYFLON TFE (grade name F-104), mean particlesize of about 500 μm, apparent density of 0.45 g/ml, melting point of326° to 328° C., specific gravity of 2.14 to 2.20, fluorine-content ofabout 76%), 0.2 part by weight of an antioxidant and 0.2 part by weightof a heat stabilizer. The mixture was premixed for 40 minutes using aV-blender, and the premixed mixture was molten and extruded with the useof a biaxially kneading-extruding machine and pelletized to give apellet.

The above-mentioned flame-retardant is the compound of the formula (I)wherein R¹, R², R³ and R⁴ are 2,6-dimethylphenyl groups, A is a1,3-phenylene group and n=1.

The above-obtained pellet was dried in an oven at 80° C. for 4 hours ormore, and the dried pellet was injection-molded using an injectionmolding machine having a mold clamping force of 100 ton at a temperatureof 240° C., at a screw rotating rate of 80 rpm and at a mold temperatureof 80° C. to give a test piece (ASTM No. 2 dumbbell piece, a bar (1/4inch in thickness, 126 mm in length), and a test piece for UL burningtest (126 mm×126 mm×1.6 mm in thickness)).

Further, the pellet was injection-molded using an injection moldingmachine having a mold clamping force (locking force) of 100 ton by aconventional injection molding method to give a three steps-formed colorplate having three species of thickness (50 mm×30 mm×1 mm/2 mm/3 mm inthickness).

Comparative Example 6

Procedure of Example 9 was repeated to obtain test pieces except forusing 19 parts by weight of a flame-retardant of a non-substitutedaromatic phosphoric acid ester of the formula (I) wherein R¹, R², R³ andR⁴ are non-substituted phenyl groups, A is a 1,3-phenylene group and nis an integer of 0 to 4 (manufactured by Daihachi Chemical IndustriesCo., Ltd., CR733S), instead of the flame-retardant of aromaticphosphoric acid ester of Example 9. The flame-retardant of thenon-substituted aromatic phosphoric acid ester comprises about 3% of thecompound having the repeating unit n of 0, about 70% of the compoundhaving the repeating unit n of 1, about 20% of the compound having therepeating unit n of 2 and about 7% of the compound having the repeatingunit n of not less than 3.

Comparative Example 7

Test pieces were obtained in the same manner as Example 9, except that19 parts by weight of a flame-retardant of a dimeric substitutedaromatic phosphoric acid ester (manufactured by Daihachi ChemicalIndustries, Co., Ltd., PX201) was employed in lieu of 19 parts by weightof the flame-retardant of Example 9. The flame-retardant is the aromaticphosphoric acid ester compound of the formula (I) wherein R¹, R², R³ andR⁴ are 2,6-dimethylphenyl groups, A is 1,4-phenylene group and n=1.

Comparative Example 8

The procedure of Example 9 was followed to obtain test pieces except foremploying 19 parts by weight of a flame-retardant of a dimericsubstituted aromatic phosphoric acid ester (manufactured by DaihachiChemical Industries, Co., Ltd., PX202) instead of 19 parts by weight ofthe flame-retardant of Example 9. The flame-retardant is the aromaticphosphoric acid ester compound of the formula (I) where R¹, R², R³ andR⁴ are 2,6-dimethylphenyl groups, A is 4,4'-biphenylylene group and n=1.

EXAMPLE 10

By using 80 parts by weight of a polycarbonate resin (manufactured byIdemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 10 parts by weight of thenon-rubber-modified styrenic resin of Example 9, and 10 parts by weightof the rubber-modified styrenic resin of Example 9, test pieces wereobtained in the similar manner as Example 9.

EXAMPLE 11

Procedure of Example 9 was followed to obtain test pieces except foremploying 80 parts by weight of a polycarbonate resin (manufactured byIdemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 7 parts by weight of thenon-rubber-modified styrenic resin of Example 9, and 13 parts by weightof the rubber-modified styrenic resin of Example 9.

EXAMPLE 12

Test pieces were obtained in the same manner as Example 9, except that60 parts by weight of a polycarbonate resin (manufactured by IdemitsuPetroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 20 parts by weight of thenon-rubber-modified styrenic resin of Example 9, and 20 parts by weightof the rubber-modified styrenic resin of Example 9 were used.

EXAMPLE 13

By using 70 parts by weight of a polycarbonate resin (manufactured byIdemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 20 parts by weight of thenon-rubber-modified styrenic resin of Example 9, and 10 parts by weightof the rubber-modified styrenic resin of Example 9, test pieces wereprepared in the same manner as Example 9.

EXAMPLE 14

The procedure of Example 9 was repeated to obtain test pieces, exceptfor employing 70 parts by weight of a polycarbonate resin (manufacturedby Idemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATEFN2700, viscosity-average molecular weight of 27,000), 15 parts byweight of the non-rubber-modified styrenic resin of Example 9, 15 partsby weight of the rubber-modified styrenic resin of Example 9, 25 partsby weight of the flame-retardant of Example 9, and 0.6 part by weight ofpolytetrafluoroethylene of Example 9.

EXAMPLE15

Test pieces were prepared in the similar manner as Example 9, exceptthat 60 parts by weight of a polycarbonate resin (manufactured byIdemitsu Petroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), 20 parts by weight of thenon-rubber-modified styrenic resin of Example 9, 20 parts by weight ofthe rubber-modified styrenic resin of Example 9, and 16 parts by weightof the flame-retardant of Example 9 were used.

EXAMPLE 16

Test pieces were obtained in the same manner as Example 9, except that9.5 parts by weight of the flame-retardant of Example 1 and 9.5 parts byweight of the flame-retardant of Example 9 were used instead of 19 partsby weight of the flame retarder of Example 9.

Comparative Example 9

The procedure of Example 9 was followed to obtain test pieces, exceptthat a thermoplastic resin composition was prepared by using (a) 40parts by weight of a polycarbonate resin (manufactured by IdemitsuPetroleum Chemicals Co., Ltd., IDEMITSU POLYCARBONATE FN2700,viscosity-average molecular weight of 27,000), (b) as thenon-rubber-modified styrenic resin, 30 parts by weight of a copolymer(weight-average molecular weight of 90,000) obtained bysuspension-polymerizing 25 parts by weight of styrene, 50 parts byweight of α-methylstyrene and 25 parts by weight of acrylonitrile, and(c) as the rubber-modified styrenic resin, 30 parts by weight of agrafted copolymer obtained by emulsion-polymerizing 45 parts by weightof styrene and 15 parts by weight of acrylonitrile in the presence of apolybutadiene rubber latex (30 parts by weight as a solid basis) and astyrene-butadiene copolymer rubber latex (10 parts by weight as a solidbasis), and that 19 parts by weight of the flame-retardant of phosphoricacid ester of Comparative Example 6 was employed.

Comparative Example 10

By using 95 parts by weight of the polycarbonate resin of Example 9, 2.5parts by weight of the non-rubber-modified styrenic resin of Example 9and 2.5 parts by weight of the rubber-modified styrenic resin of Example9, as well as 19 parts by weight of the flame-retardant of phosphoricacid ester of Comparative Example 7, test pieces were prepared in thesimilar manner as Example 9.

Comparative Example 11

Test pieces were obtained in the same manner as Example 9, except that15 parts by weight of the non-rubber-modified styrenic resin of Example9, and 15 parts by weight of the rubber-modified styrenic resin ofExample 9 were employed, and that the polytetrafluoroethylene was notused.

The characteristics of the test pieces each obtained in Examples 9 to 16and Comparative Examples 6 to 11 were evaluated. The results are shownin Table 2. In Table 2, the styrenic resins each used in Example 9 andComparative Example 9 are designated in the line of "Species of styrenicresin" by the symbols "(4)" and "(5)" respectively, and the total amountof the non-rubber-modified styrenic resin and the rubber-modifiedstyrenic resin is set forth in the line of "Amount of styrenic resin".In the line of "Species of flame-retardant", the flame-retardants eachemployed in Example 9, Comparative Example 6, Comparative Example 7,Comparative Example 8 and Example 16 are defined by the symbols "(4)","(5)", "(6)", "(7)" and "(8)" separately.

                                      TABLE 2                                     __________________________________________________________________________               Com.                                                                              Comp.                                                                             Comp.                           Comp.                                                                             Com.                                                                              Com.                       Ex. 9                                                                            Ex. 6                                                                             Ex. 7                                                                             Ex. 8                                                                             Ex. 10                                                                            Ex. 11                                                                            Ex. 12                                                                            Ex. 13                                                                            Ex. 14                                                                            Ex. 15                                                                            Ex. 16                                                                            Ex. 9                                                                             Ex.                                                                               Ex.                __________________________________________________________________________                                                               11                 Polycarbonate                                                                         70 70  70  70  80  80  60  70  70  60  70  40  95  70                 Species of                                                                            (4)                                                                              (4) (4) (4) (4) (4) (4) (4) (4) (4) (4) (5) (4) (4)                styrenic resin                                                                Amount of                                                                             30 30  30  30  20  20  40  30  30  40  30  60  5   30                 styrenic resin                                                                Species of                                                                            (4)                                                                              (5) (6) (7) (4) (4) (4) (4) (4) (4) (8) (5) (6) (4)                flame-retarder                                                                Amount of                                                                             19 19  19  19  19  19  19  19  25  16  19  19  19  19                 flame-retarder                                                                Fluororesin                                                                           0.4                                                                              0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.6 0.4 0.4 0.4 0.4 0                  Tensile elon-                                                                         53 72  36  75  60  63  105 38  28  50  46  110 15  50                 gation                                                                        Bending 268                                                                              256 281 242 280 275 255 282 285 265 279 178 320 271                elasticity                                                                    (×10.sup.2)                                                             Impact strength                                                                       9.2                                                                              7.2 9.3 9.5 10.5                                                                              11.2                                                                              7.2 6.8 7.8 10.9                                                                              7.6 4.0 14.0                                                                              8.9                Thermal 85 77  86  96  89  87  78  87  79  71  81  68  98  86                 deforming                                                                     temperature                                                                   (°C.)                                                                  Flame   v-70                                                                             v-0 v-0 v-1 v-0 v-0 v-0 v-0 v-0 v-0 v-0 v-2 v-0 v-2                resistance                                                                    (UL)                                                                          Light   1.7                                                                              3.1 1.8 2.2 1.7 1.8 2.0 1.5 2.1 1.2 1.8 --  3.8 1.5                resistance                                                                    (ΔE)                                                                    Spiral flow                                                                           244                                                                              260 210 190 225 215 286 260 318 278 272 360 105 250                length                                                                        (mm)                                                                          __________________________________________________________________________

As apparent from Table 2, the compositions obtained in Examples 9 to 16have high melt fluidity and are useful for molding a shaped articlehaving high flame-retardancy and light resistance which is large shapedor thin shaped and is not liable to be discolored.

The composition obtained in Comparative Example 6 has not only low lightresistance but also poor heat resistance and impact resistance incomparison with the composition obtained in Example 9. Further, theflame-retardant employed in Comparative Example 6 is in a liquid form,so that the working properties during the premixing process is decreasedor reduced. As compared with the composition obtained in Example 9, thecomposition obtained in Comparative Example 7 has lower melt fluidityand still less smaller tensile elongation. The composition obtained inComparative Example 8 is insufficient in flame-resistance and has lowerflowability. In the composition of Comparative Example 9, theflame-retardancy is poor although with high melt fluidity, and thecomposition of Comparative Example 10 has poor melt fluidity thoughhaving high heat resistance. The composition obtained in ComparativeExample 11 lacks sufficient flame-retardancy and causes a drip in theflame-resistance test. In the shaped articles each obtained in Examples9 to 16, no spot was formed in the water discoloring resistance test,and to the contrary, as for the shaped articles obtained in ComparativeExamples 6 and 10, white spots were formed in the water discoloringresistance test.

What is claimed is:
 1. A flame-retardant resin composition whichcomprises:10 to 30 parts by weight of a flame-retardant compositioncomprising an aromatic phosphoric acid ester shown by the followingformula (I); ##STR3## wherein R¹, R², R³ and R⁴ independently representa phenyl group substituted with 0 to 3 alkyl groups each having 1 to 3carbon atoms, A represents a 1,3-phenylene group and n denotes aninteger of 0 to 5; R¹, R², R³ and R⁴ comprise at least (a) a2,4-dimethylphenyl group, a 3,4-dimethylphenyl group or a3,5-dimethylphenyl group and (b) a monoalkylphenyl group; and theproportion of the amount of the 2,4-dimethylphenyl group, the3,4-dimethylphenyl group and the 3,5-dimethylphenyl group relative tothe amount of the monoalkylphenyl group in R¹, R², R³ and R⁴ is suchthat the former/the latter is 60/40 to 90/10 (mole percent) wherein 0 to10 mole percent has the repeating unit n of 0, 40 to 90 mole percent hasthe repeating unit n of 1, 5 to 40 mole percent has the repeating unit nof 2 and 5 to 25 mole percent has the repeating unit of n of not lessthan 3;
 0. 1 to 2 parts by weight of polytetrafluoroethylene (D); and100parts by weight of a mixture of thermoplastic resins comprising 50 to90% by weight of an aromatic polycarbonate resin (A) and 10 to 50 % byweight of a stytonic resin (B).
 2. A flame-retardant resin compositionaccording to claim 1, where in said compound (i), the proportion of theamount of the 2,4-dialkylphenyl group, the 3,4-dialkylphenyl group andthe 3,5-dialkylphenyl group is not less than 50 mole percent based onthe total amount of R¹, R², R³ and R⁴.
 3. A flame-retardant resincomposition according to claim 1, wherein said alkyl group is methylgroup or ethyl group.
 4. A flame-retardant resin composition accordingto claim 1, wherein said aromatic polycarbonate (A) is a bisphenol Atype aromatic polycarbonate.
 5. A flame-retardant resin compositionaccording claim 1, wherein said fluororesin (D) is a powderypolytetrafluoroethylene.
 6. A flame-retardant resin compositionaccording to claim 1, wherein said styrenic resin (B) comprises anon-rubber-modified styrenic resin (B1) and a rubber-modified styrenicresin (B2) in such a proportion that the former/the latter is 0/100 to75/25 (by weight).
 7. A flame-retardant resin composition according toclaim 6, wherein said non-rubber-modified styrenic resin (B1) is acopolymer obtainable by polymerizing 50 to 90% by weight of an aromaticvinyl monomer (B1a), 10 to 40% by weight of a vinyl cyanide monomer(B1b) and 0 to 40% by weight of a copolymerizable vinyl monomer (B1C).8. A flame-retardant resin composition according to claim 6, whereinsaid rubber-modified styrenic resin (B2) is a grafted copolymerobtainable by graft-polymerizing 35 to 95% by weight of a polymerizablevinyl monomer comprising at least an aromatic vinyl monomer (B1a) to 5to 65% by weight of a rubber-like polymer (B21) having a glasstransition temperature (Tg) of not higher than 0° C.
 9. Aflame-retardant resin composition according to claim 1 wherein saidflame-retardant (C) comprises a mixture of phosphoric acid estersdiffering in the repeating unit n, and the average value of n is 0.5 to2.0.
 10. A flame-retardant resin composition according to claim 1,wherein the ratio of the amount of the 2,4-dialkylphenyl group, the3,4-dialkylphenyl group and the 3,5-dialkylphenyl group relative to theamount of said monoalkylphenyl group is such that the former/the latteris 60/40 to 80/20 (mole percent).
 11. A flame-retardant resincomposition according to claim 1, wherein said flame-retardant comprises1 to 10 mole percent of the compound of the formula (I) having therepeating unit n of 0, 40 to 90 mole percent of the compound of theformula (I) having the repeating unit n of 1, 5 to 40 mole percent ofthe compound of the formula (I) having the repeating unit n of 2, and 5to 25 mole percent of the compound of the formula (I) having therepeating unit n of not less than 3.